Fluted filter medium and process for its manufacture

ABSTRACT

A fluted filter medium ( 74 ) comprising a corrugated filter sheet, where each flute ( 120 ) has an end closure defined by a regular fold arrangement in the corresponding corrugation. Each regular fold arrangement has at least four folds. A process for manufacturing the fluted filter medium comprising deforming a portion of each corrugation to define at least one foldable tip, and folding the said tip in order to close the corrugation.

This application is being filed as a PCT International PatentApplication in the name of Donaldson Company, Inc., a U.S. nationalcorporation and resident, (Applicant for all countries except US);Patrick Golden, a U.S. resident and citizen (Applicant for US only);Gregory L. Reichter, a U.S. resident and citizen (Applicant for US only)and Daniel T. Risch, a U.S. resident and citizen (Applicant for U.S.only), on 31 Jan. 2003, designating all countries and claiming priorityto U.S. 60/395,009 filed 10 Jul. 2002.

FIELD OF THE DISCLOSURE

The present disclosure relates to filter media for use in filteringliquids or gases. The disclosure particularly relates to such media thatutilizes a corrugated structure, to define filtration flutes orsurfaces. Specifically, the disclosure relates to techniques formodifying such flutes in selected portions thereof, and to resultingstructures.

BACKGROUND

Fluid streams, such as air and liquid, carry contaminant materialtherein. In many instances, it is desired to filter some or all of thecontaminant material from the fluid stream. For example, air flowstreams to engines for motorized vehicles or for power generationequipment, gas streams to gas turbine systems and air streams to variouscombustion furnaces, carry particulate contaminant therein that shouldbe filtered. Also liquid streams in engine lube systems, hydraulicsystems, coolant systems or fuel systems, carry contaminant, that shouldbe filtered. It is preferred for such systems, that selected contaminantmaterial be removed from (or have its level reduced in) the fluid. Avariety of fluid filter (air or liquid filter) arrangements have beendeveloped for contaminant reduction. In general, however, continuedimprovements are sought.

SUMMARY

The present disclosure concerns folded flute ends of fluted filtermedia, and to techniques for folding. It also concerns preferred filterarrangements constructed utilizing media having flutes with folded ends.

A variety of methods for folding media are described herein. In general,a common feature to each is that the media folding includes a step ofdeforming a media flute, typically through an indentation or projectionagainst an outside surface of the flute. Follow up folding steps causepreferred folded configurations to result.

A portion of this disclosure is based upon, and priority is claimed to,U.S. provisional application Ser. No. 60/395,009, filed Jul. 10, 2002.In that priority document, a preferred folded or darted mediaconfiguration was shown, along with a process for forming the preferredconfiguration. In general, the process involved directing an indentationpin arrangement against a ridge of a corrugation.

In addition to the disclosure of U.S. provisional application Ser. No.60/395,009 contained herein, there are provided additional techniquesapplicable to provide preferred fold arrangements. Certain of thesetechniques are generally referred to as “supported” processes, methodsor techniques and relate to supporting a portion of the flute in thevicinity of the deformation. In addition, preferred arrangements forproviding flute support during deformation, are described.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings, relative dimensions and material thicknessmay be shown exaggerated for clarity.

FIG. 1 is a schematic perspective view of prior art z-filter media.

FIG. 2 is a schematic upstream end view of a filter element utilizingcoiled media according to FIG. 1.

FIG. 3 is a schematic outlet end view of the arrangement depicted inFIG. 1.

FIG. 4 is a schematic enlarged fragmentary view of a portion ofcorrugated media attached to a portion of uncorrugated media, in az-filter construction.

FIG. 5 is a figure from a prior art reference, specifically Yamada, etal. U.S. Pat. No. 5,562,825.

FIG. 6 is an enlarged view of a portion of the media depicted in FIG. 4.

FIG. 7 is a schematic view of a process, including method steps, usableto prepare z-filter media having folded ends of selected flutes.

FIG. 8 is a cross-sectional view of a flute after contact with aninverter wheel of FIG. 7, and before contact with a folder wheel of FIG.7.

FIG. 9 is a cross-sectional view of a flute taken along line 9-9 of FIG.8.

FIG. 10 is a cross-sectional view of a flute taken along line 10-10,FIG. 8.

FIG. 11 is a cross-sectional view of a flute after contact with a folderwheel of FIG. 7.

FIG. 12 is a cross-sectional view of a flute taken along line 12-12 ofFIG. 11.

FIG. 13 is a cross-sectional view of a flute taken along line 13-13 ofFIG. 11.

FIG. 14 is a cross-sectional view of a flute taken along line 14-14 ofFIG. 11.

FIG. 15 is an end view of a folded flute depicted in FIG. 11.

FIG. 16 is a side elevational view of a creaser wheel, i.e., one of thecomponents utilized in a manufacturing approach depicted in FIG. 7.

FIG. 17 is a cross-sectional view of a portion of filter media aftercontact with the creaser wheel of FIG. 16 and before contact with theinverter wheel of FIG. 20.

FIG. 18 is a cross-sectional view of a flute taken along line 18-18 ofFIG. 17.

FIG. 19 is a cross-sectional view of a flute taken along line 19-19,FIG. 17.

FIG. 20 is a cross-sectional view of a flute inverter wheel of FIG. 7.

FIG. 21 is an enlarged, partially cross-sectional, view of an end of oneof the teeth shown in the flute inverter wheel of FIG. 20.

FIG. 22 is a perspective view of the wheel depicted in FIG. 20.

FIG. 23 is a side elevational view of the folder wheel of FIG. 7.

FIG. 24 is an enlarged end view of a portion of the folder wheel of FIG.23.

FIG. 25 is a schematic, perspective view of a portion of filter mediausable in filter elements of the type shown in FIGS. 26 and 27.

FIG. 26 is a schematic, perspective view of a filter element utilizingfluted filter media having folded ends in accord with the descriptionsherein.

FIG. 27 is a schematic, perspective view of a second filter elementutilizing fluted filter media constructed in accord with the principlesdescribed herein, and having folded ends.

FIG. 27A is a schematic view of one embodiment of a system in which aircleaners having elements for filter media of the type described hereinare used.

FIG. 28 is a schematic view of corrugated filter media provided withoutside support during an indentation process, according to the presentdisclosure.

FIG. 29 is a schematic depiction of a corrugation filter media providedwith inside support during an indentation process, according to thepresent disclosure.

FIG. 30 is a schematic depiction of corrugated media shown supported byan encapsulation process, during the step of indentation according tothe present disclosure.

FIG. 31 is a schematic depiction of a process involving supported media,according to the present disclosure.

FIG. 32 is a perspective view of a outside support/indentation rolleraccording to the present disclosure.

FIG. 33 is a side view of the roller depicted in FIG. 32.

FIG. 34 is an enlarged view of a portion of the roller depicted in FIG.33.

FIG. 35 is a schematic partially cross-sectional view of an outsidesupport indentation roller taken generally from the view point of line35-35, FIG. 34.

FIG. 36 is a schematic depiction of an outside supported darting processusing the roller of FIGS. 32-35.

FIG. 36A is an enlarged fragmentary view of a portion of the processdepicted in FIG. 36.

FIG. 37 is a schematic, perspective, view of an indentation pinarrangement utilized in the supporting/indentation roller of FIG. 32.

FIG. 38 is an end view of the indentation pin arrangement depicted inFIG. 37.

FIG. 39 is a side view of a stationary cam wheel used in the outsidesupport/indentation roller of FIG. 32.

FIG. 40 is a perspective view of the stationary cam depicted in FIG. 39.

FIG. 41 is a perspective view of an inside support roller.

FIG. 42 is an end view of the inside support roller of FIG. 41.

FIG. 43 is an enlarged, fragmentary view of a portion of the rollerdepicted in FIG. 42.

FIG. 44 is a schematic depiction of an inside support indentationprocess.

FIG. 45 is an enlarged view of a portion of FIG. 44.

FIG. 46 is a schematic depiction of a step of encapsulated supportaccording to the present disclosure.

FIG. 47 is a schematic depiction of an edge folding process according tocertain applications of techniques described in the present disclosure.

FIG. 48 is a schematic depiction of an alternate edge folding process.

FIG. 49 is a schematic depiction of various flute definitions.

DETAILED DESCRIPTION I. Media Configurations Using Corrugated Media,Generally

Fluted filter media can be used to provide fluid filter constructions ina variety of manners. One well known manner is as a z-filterconstruction. The term “z-filter construction” as used herein, is meantto refer to a filter construction in which individual ones ofcorrugated, folded or otherwise formed filter flutes are used to definesets of parallel longitudinal inlet and outlet filter flutes for fluidflow through the media. Some examples of z-filter media are provided inU.S. Pat Nos. 5,820,646; 5,772,883; 5,902,364; 5,792,247; 5,895,574;6,210,469; 6,190,432; 6,350,296; 6,179,890; 6,235,195; Des. 399,944;Des. 428,128; Des. 396,098; Des. 398,046; D437,401.

One particular type of z-filter media, utilizes two specific mediacomponents joined together, to form the media construction. The twocomponents are: a corrugated (or fluted) sheet; and, a non-corrugated(or facing) sheet. The corrugated (or fluted) media and non-corrugated(or facing) sheet together, are used to define the parallel inlet andoutlet flutes. In some instances, the corrugated sheet andnon-corrugated sheet are secured together and are then coiled to form az-filter media construction. Such arrangements are described, forexample, in U.S. Pat. No. 6,235,195 and 6,179,890. In certain otherarrangements, some non-coiled sections of corrugated media secured toflat media, are stacked on one another, to create a filter construction.An example of this is described in FIG. 11 of U.S. Pat. No. 5,820,646.

The term “corrugated” used herein to refer to structure in media, ismeant to refer to a structure resulting from passing the media betweentwo corrugation rollers, i.e., into a nip or bite between two rollerseach of which has surface features appropriate to cause a corrugationaffect in the resulting media. The term “corrugation” is not meant torefer to flutes that are folded or otherwise formed by techniques notinvolving passage of media into a bite between corrugation rollers.However, the term “corrugated” is meant to apply even if the media isfurther modified or deformed after corrugation, for example by thefolding techniques described herein.

Corrugated media is a specific form of fluted media. Fluted media ismedia which has individual flutes (for example formed by corrugating orfolding) extending thereacross.

Serviceable filter element configurations utilizing z-filter media aresometimes referred to as “straight through flow configurations” or byvariants thereof. In general in this context what is meant is that theserviceable filtered elements generally have an inlet flow face and anopposite exit flow face, with flow entering and exiting the filtercartridge in generally the same straight through direction. The term“serviceable” in this context is meant to refer to a media containingfilter cartridge that is periodically removed and replaced from acorresponding fluid cleaner.

The straight through flow configuration is in contrast to serviceablefilter cartridges such as cylindrical pleated filter cartridges of thetype shown in U.S. Pat. No. 6,039,778, incorporated herein by reference,in which the flow generally makes a turn as its passes through theserviceable cartridge. That is, in a U.S. Pat. No. 6,039,778 filter theflow enters the cylindrical filter cartridge through a side, and thenturns to exit through an end face (in forward-flow systems). Inreverse-flow systems, the flow enters the serviceable cylindricalcartridge through an end face and then turns to exit through a side ofthe filter cartridge. An example of a reverse-flow system is shown inU.S. Pat. No. 5,613,992, incorporated by reference herein.

An example of a typical prior art z-filter media construction is shownin FIGS. 1-4. FIG. 1 is based on the disclosure of prior art U.S. Pat.No. 5,820,646, at FIG. 1. FIG. 2 is an enlarged end view of an inlet endportion of a straight through flow filter element using a mediaconstruction made with the media shown in FIG. 1. FIG. 3 is an enlargedend view of and analogous to FIG. 2, but of an opposite, outlet, end.FIG. 4 is an enlarged, schematic, view of a combination of corrugatedsheet and non-corrugated sheets.

The term “z-filter media construction” and variants thereof as usedherein, is meant to refer to any or all of: a web of corrugated orotherwise fluted media secured to non-corrugated (facing) media withappropriate sealing to allow for definition of inlet and outlet flutes;or, such a media coiled or otherwise constructed or formed into a threedimensional network of inlet and outlet flutes; and/or, a filterconstruction including such media.

Referring to FIG. 1, the z-filter media construction 1 depictedcomprises a corrugated sheet 3, and a non-corrugated sheet 4 secured toone another. The corrugated sheet 3 is secured to the non-corrugatedsheet 4 such that individual flutes or corrugations 7 (comprising ridges7 a and troughs 7 b when viewed toward side 3 a of sheet 3) extendacross the non-corrugated sheet 4 between opposite ends or edges 8 and9. For the final product, it is a matter of choice whether end (or edge)8 or end (or edge) 9 is the upstream end or edge. For purposes of thefollowing discussion, it will be assumed that edge 8 is chosen to be theupstream edge and edge 9 is chosen to be the downstream edge, in theresulting filter media construction. Thus, arrows 10 indicate thedirection of fluid flow, during filtering.

Referring to FIG. 1, the corrugated sheet 3 has first and secondopposite sides or surfaces 3 a, 3 b. The second side 3 b is the sidedirected toward the non-corrugated sheet 4, during initial assembly ofthe corrugated sheet 3/flat sheet 4 combination as discussed below;i.e., when the corrugated sheet 3 is first brought into contact with thenon-corrugated sheet 4. At the upstream edge 8, flutes 11 defined bytroughs 7 b of the corrugations 7 above the corrugated sheet 3, i.e., atside 3 a of sheet 3 are open to fluid flow therein in the direction ofarrows 12, along the upstream edge 8, but are closed to fluid flowtherefrom along the downstream edge 9, by barrier 14, in this instancesealant 14 a. On the other hand, flutes 15, defined by corrugations 7 aon the opposite side 3 b of the corrugated sheet 3 from flutes 11, areclosed to entrance of fluid therein along the upstream edge 8, bybarrier 16, in this instance sealant 16 a, but are open to fluid flowoutwardly therefrom, along edge 9, by the absence of any sealant at thislocation.

Of course in the arrangement of FIG. 1, the media is shown not securedin an overall three-dimensional filter element cartridge structure, thatwould complete creation of the isolated parallel flutes 11, 15. This isshown in fragmentary, schematic, in FIG. 2. Referring to FIG. 2, themedia construction 1 is now shown configured in an overallthree-dimensional media pack 20. In general media pack 20, for theembodiment shown, would comprise the media construction 1 of FIG. 1,coiled about itself to create a cylindrical fluted-construction 21. Acomplete drawing would typically show a circular or obround filter body.In FIG. 2, only a portion of such a coiled construction 21 is depicted,in particular a portion when viewed toward an upstream surface 22.Herein the term “upstream” when used in this or similar contexts torefer to a surface or edge, is meant to refer to the surface or edgetoward which fluid is directed, for a filtering process. That is, theupstream surface or edge is the surface or edge at which the fluid to befiltered enters the z-filter construction 21. Analogously, the term“downstream” when used to refer to an edge or surface, is meant to referto the edge or surface of a construction 21 from which filtered fluidexits the filtered media construction 21, during use.

It is noted that in FIGS. 2 and 3, the flutes 11, 15 are depictedschematically, as if they have triangular, cross-sections, forsimplicity. The actual curved shape of FIG. 1 would be present in theactual filter.

Referring to FIG. 2, at upstream edge 8 or along upstream surface 22,the fluid flow openings in inlet flutes 11 are generally indicated bythe absence of barrier or sealant. Thus inlet flutes 11 are open to thepassage of fluid flow therein. The closed upstream ends of exit flutes15 are also shown, by the presence of a barrier, in this instancesealant. Thus, fluid flow directed against upstream surface 22 can onlypass into the media construction 20, for filtering, by entering theinlet flutes 11. It is noted that in some instances, at the upstreamedge 8, the outlet flutes may not be sealed immediately at the edge 8,but rather may be sealed by a sealant spaced inwardly from the edge 8, aportion of the way down the length of the corresponding flute. Anexample of this is shown, for example, in U.S. Pat. No. 5,820,646, atFIG. 16 thereof. In general, the inlet end of an exit flute will beconsidered sealed, as long as the sealant or other structure closing theflute is located (relative to edge 8) either at the edge or no more than25% (preferably no more than 10%) of the distance between the upstreamedge 8 and the opposite downstream edge 9. Usually the sealing is at theedge 8. The description “no more than 25% (or 10%) of the distancebetween the upstream edge and the opposite downstream edge 9” in thiscontext is meant to include sealing at edge 8.

Referring to FIG. 3, the exit edge 9 of the media, forming exit end or23 of the filter construction 21. The exit flutes 15 are shown open, andthe inlet flutes 11 are shown closed by barrier or sealant. The inletflutes 11 will be considered sealed at the downstream ends, as long asthe sealant material or other structure closing the flute, is at theexit edge 9, or within a distance from the edge 9 corresponding to nomore than 25% of the distance between the opposite edges 8 and 9. Fortypical, preferred, embodiments the sealed end of each flute 8, 9 wouldbe sealed by sealant positioned at a location within a distance from theclosest edge of no more than 10% of the flute length from edge 8 to edge9. Usually the sealing is at the edge 9. The description “no more than25% (or 10%) of the flute length from edge 8 to edge 9” in this context,is meant to include sealing at edge 9.

In general, the corrugated sheet 3, FIG. 1 is of a type generallycharacterized herein as having a regular, curved, wave pattern of flutesor corrugations. The term “wave pattern” in this context, is meant torefer to a flute or corrugated pattern of alternating troughs 7 b andridges 7 a. The term “regular” in this context is meant to refer to thefact that the pairs of troughs and ridges (7 b, 7 a) alternate withgenerally the same repeating corrugation (or flute) shape and size.(Also, typically each trough 7 b is substantially an inverse of eachridge 7 a.) The term “regular” is thus meant to indicate that thecorrugation (or flute) pattern comprises troughs and ridges with eachpair (comprising an adjacent trough and ridge) repeating, withoutsubstantial modification in size and shape of the corrugations along atleast 70% of the length of the flutes. The term “substantial” in thiscontext, refers to a modification resulting from a change in the processor form used to create the corrugated or fluted sheet, as opposed tominor variations from the fact that the media sheet 3 is flexible. Withrespect to the characterization of a repeating pattern, it is not meantthat in any given filter construction, an equal number of ridges andtroughs is present. The media could be terminated, for example, betweena pair comprising a ridge and a trough, or partially along a paircomprising a ridge and a trough. (For example, in FIG. 1 the media 1depicted in fragmentary has eight complete ridges 7 a and seven completetroughs 7 b.) Also, the ends of the troughs and ridges may vary from oneanother. Such variations in ends are disregarded in the definitions.

In the context of the characterization of a “curved” wave pattern ofcorrugations, the term “curved” is meant to refer to a corrugationpattern that is not the result of a folded or creased shape provided tothe media, but rather the apex 7 a of each ridge and the bottom 7 a ofeach trough is formed along a radiused curve. A typical radius for suchz-filter media would be at least 0.25 mm and typically be not more than3 mm.

An additional characteristic of the particular regular, curved, wavepattern depicted in FIG. 4, for the corrugated sheet 3, is that atapproximately a midpoint 30 between each trough and each adjacent ridge,along most of the length of the flutes, is located a transition regionwhere the curvature inverts. For example, viewing face 3 a, FIG. 1,trough 7 b is a concave region, and ridge 7 a is a convex region. Ofcourse when viewed toward face 3 b, trough 7 b of side 3 a forms aridge; and, ridge 7 a of face 3 a, forms a trough.

A characteristic of the particular regular, curved, wave patterncorrugated sheet shown in Figs. IA, is that the individual corrugationsare generally straight. By “straight” in this context, it is meant thatthrough at least 70%, typically at least 80% of the length between edges8 and 9, the troughs do not change substantially in cross-section. Theterm “straight” in reference to corrugation pattern shown in FIGS. 1-4,in part distinguishes the pattern from the tapered flutes of corrugatedmedia described in FIG. 1 of WO 97/40918. The tapered flutes of FIG. 1of WO 97/40918 would be a curved wave pattern, but not a “regular”pattern, or a pattern of straight flutes, as the terms are used herein.

For the particular arrangement shown herein in FIG. 1, the parallelcorrugations are generally straight completely across the media, fromedge 8 to edge 9. However, herein embodiments are shown in whichstraight flutes or corrugations are deformed or folded at selectedlocations, especially at ends. Again, modifications at flute ends aregenerally disregarded in the above definitions of “regular,” “curved”and “wave pattern.”

Attention is again directed to FIG. 3 in which media pack 20 is depictedfrom a viewpoint directed toward downstream end 23 defined by edge 9 ofthe z-filter media construction 1. At this end or surface 23, the exitflutes 15 are depicted open and unsealed, and the entrance flutes 11,are shown closed by a barrier, in this case, by sealant. Thus, the onlyway fluid can exit from downstream end 23 is by flow outwardly from anopen exit flute 15.

As a result of the above described construction, fluid which enters theinlet face 22 can only exit from the opposite exit face 23, if the fluidhas passed through the filter media 3, 4. This, in general, is acharacteristic of a z-filter media construction in use namely: (a)individual generally parallel flutes are defined by a media, for examplecorrugated media; and, (b) a closure pattern is provided closing exitflutes at the upstream end and closing inlet flutes at the downstreamend, forcing fluid flow (with filtering) through one of the media sheetsin order for the fluid to exit from the media pack.

In typical applications involving z-filter media, the media is eithersurrounded by an impermeable shell (as in U.S. Pat. No. 5,820,646), orseals are used at appropriate locations, or both, to prevent fluid flowfrom going around the media, from a fluid inlet to a fluid outlet.

Attention is again directed to FIG. 4, which is an enlarged,fragmentary, schematic, end view of the Z-filter media construction 1,showing the corrugated sheet 3 and the non-corrugated sheet 4, but notbarrier or sealant. Again, the configuration of the corrugated sheet, inFIG. 4, will sometimes be referred to herein as a regular, curved, wavepattern of straight flutes.

Z-filter constructions which do not utilize straight, regular curvedwave pattern corrugation shapes are known. For example in Yamada et al.U.S. Pat. No. 5,562,825 corrugation patterns which utilize somewhatsemicircular (in cross section) inlet flutes adjacent narrow V-shaped(with curved sides) exit flutes are shown (see FIGS. 1 and 3, of U.S.Pat. No. 5,562,825). In Matsumoto, et al. U.S. Pat. No. 5,049,326circular (in cross-section) or tubular flutes defined by one sheethaving half tubes attached to another sheet having half tubes, with flatregions between the resulting parallel, straight, flutes are shown, seeFIG. 2 of Matsumoto '326. In Ishii, et al. U.S. Pat. No. 4,925,561(FIG. 1) flutes folded to have a rectangular cross section are shown, inwhich the flutes taper along their lengths. Finally, in WO 97/40918(FIG. 1), flutes or parallel corrugations which have a curved, wavepatterns (from adjacent curved convex and concave troughs) but whichtaper along their lengths (and thus are not straight) are shown.

Before proceeding further with this description, the nature of thefilter media is briefly discussed. In general the filter media is arelatively flexible material, typically a non-woven fibrous material (ofcellulose fibers, synthetic fibers or both) typically including a resintherein, sometimes treated with additional materials. Thus, it can beconformed or configured into the various folded or corrugated patterns,without unacceptable media damage. Also, it can be readily coiled orotherwise configured for use, again without unacceptable media damage.Of course, it must be of a nature such that it will maintain acorrugated or folded configuration, during use.

In the corrugation process, an inelastic deformation is caused to themedia. This prevents the media from returning to its original shape.However, once the tension is released the flute or corrugations willtend to spring back, recovering only a portion of the stretch andbending that has occurred. Thus, facing (noncorrugated) sheet is tackedto the fluted sheet, to inhibit this spring back.

Also, in general the media contains a resin. During the corrugationprocess, the media can be heated to above the glass transition point ofthe resin. When the resin then cools, it will help to maintain thefluted shapes.

Both of these techniques are generally known in practice, with respectto the formation of corrugated media.

An issue with respect to z-filter constructions relates to closing ofthe individual flute ends. In many instances a sealant or adhesive isprovided, to accomplish the closure. As is apparent from the discussionabove, in typical z-filter media, especially that which uses straightflutes as opposed to tapered flutes, large sealant surface areas (andvolume) at both the upstream end and the downstream end are needed. Highquality seals at these locations are critical to proper operation of themedia structure that results. The high sealant volume and area, createsissues with respect to this. In addition, the relatively large,impermeable surface area to fluid flow represented by the sealant areas,generally positioned perpendicular to flow through the media pack,create restriction to fluid flow.

With respect to a particular configuration of straight fluted media,Yamada, et al. suggest addressing this issue at the downstream end ofthe media, by flattening the two media sheets together into a parallelconfiguration, see FIGS. 1 and 4 of Yamada, et al, U.S. Pat. No.5,562,825. Yamada, et al. FIG. 4 is depicted herein as FIG. 5, withoutreference numerals. A flattening such as that found in Yamada, et al.,leads to less sealant volume due to the crushing and potentially lessleakage through the sealant, due to the compression.

In the disclosure of WO 97/40918, incorporated herein by reference, itwas suggested that this sealant or closed volume/area issue could beaddressed (at least with media having a regular, curved, wave pattern)by crushing along a sealant bead and then slitting.

A reference which generally shows a different type of crushing of flutesis U.K. 703,823, published Feb. 10, 1954.

Attention is now directed to FIG. 6, in which a z-filter mediaconstruction 40 utilizing a regular, curved, wave pattern corrugatedsheet 43, and a non-corrugated flat sheet 44, is depicted. The distanceD1, between points 50 and 51, defines the extension of flat media 44 inregion 52 underneath a given corrugated flute 53. The length D2 of thearcuate media for the corrugated flute 53, over the same distance D1 isof course larger than D1, due to the shape of the corrugated flute 53.For a typical regular shaped media used in fluted filter applications,the linear length D2 of the media 53 between points 50 and 51 willgenerally be at least 1.2 times D1. Typically, D2 would be within arange of 1.2-2.0, inclusive. One particularly convenient arrangement forair filters has a configuration in which D2 is about 1.25-1.35×D1. Suchmedia has, for example, been used commercially in Donaldson Powercore™Z-filter arrangements. Herein the ratio D2/D1 will sometimes becharacterized as the flute/flat ratio or medium draw for the corrugatedmedia.

In the corrugated cardboard industry, various standard flutes have beendefined. For example the standard E flute, standard X flute, standard Bflute, standard C flute and standard A flute. FIG. 49, attached, incombination with Table A below provides definitions of these flutes.

Donaldson Company, Inc., (DCI) the assignee of the present disclosure,has used variations of the standard A and standard B flutes, in avariety of filter arrangements. These flutes are also defined in FIG. 49and Table A. TABLE A (Flute definitions for FIG. 49) DCI A Flute:Flute/flat = 1.52:1; The Radii (R) are as follows: R1000 = .0675 inch(1.715 mm); R1001 = .0581 inch (1.476 mm); R1002 = .0575 inch (1.461mm); R1003 = .0681 inch (1.730 mm); DCI B Flute: Flute/flat = 1.32:1;The Radii (R) are as follows: R1004 = .0600 inch (1.524 mm); R1005 =.0520 inch (1.321 mm); R1006 = .0500 inch (1.270 mm); R1007 = .0620 inch(1.575 mm); Std. E Flute: Flute/flat = 1.24:1; The Radii (R) are asfollows: R1008 = .0200 inch (.508 mm); R1009 = .0300 inch (.762 mm);R1010 = .0100 inch (.254 mm); R1011 = .0400 inch (1.016 mm); Std. XFlute: Flute/flat = 1.29:1; The Radii (R) are as follows: R1012 = .0250inch (.635 mm); R1013 = .0150 inch (.381 mm); Std. B Flute: Flute/flat =1.29:1; The Radii (R) are as follows: R1014 = .0410 inch (1.041 mm);R1015 = .0310 inch (.7874 mm); R1016 = .0310 inch (.7874 mm); Std. CFlute: Flute/flat = 1.46:1; The Radii (R) are as follows: R1017 = .0720inch (1.829 mm); R1018 = .0620 inch (1.575 mm); Std. A Flute: Flute/flat= 1.53:1; The Radii (R) are as follows: R1019 = .0720 inch (1.829 mm);R1020 = .0620 inch (1.575 mm).

Of course other, standard, flutes definitions from the corrugated boxindustry are known.

In general, standard flute configurations from the corrugated boxindustry can be used to define corrugation shapes or approximatecorrugation shapes for corrugated media. Comparisons above between theDCI A flute and DCI B flute, and the corrugation industry standard A andstandard B flutes, indicate some convenient variations.

It should be apparent that once the length D2 of the corrugated media 53exceeds D1 substantially, for example becomes 1.2 D1 or larger,accomplishing a consistent parallel squeeze or configuration such asthat shown at the downstream edge in Yamada, et al., FIG. 4 herein, willbe difficult, especially with significant line speeds (30 meters perminute or more). This is in part because there is often too much mediain the corrugation 53 to line up evenly and in parallel with the flatmedia 44 in region 52 to achieve the configuration shown herein in FIG.5, (i.e. in FIG. 4 of Yamada et al. U.S. Pat. No. 5,562,825).

In general, Donaldson Company, the assignee of the present disclosure,has determined that when the relationship between the flutes ofcorrugation sheet and the flat sheet is such that the flute/flat ratioor medium draw is at least 1.2 (i.e. the corrugation length (D2) is atleast 1.2 times the linear flat sheet length (D1) in the region ofclosure, in some instances it is preferred to generate a regular foldpattern, to collapse the corrugation (flute) toward the flat sheet, andto reduce the sealant area at or near flute ends. By the term “regularfold pattern” in this context, it is meant that selected corrugated(flute) ends that are modified are folded into a regular and repeatedpattern, as opposed to merely being crushed toward the flat sheet. Onesuch regular fold pattern is illustrated herein in FIG. 15, and a methodfor generating it is described in commonly assigned U.S. provisionalapplication 60/395,009, filed Jul. 10, 2002, to which priority isclaimed. Such a fold pattern will generally be referred to herein as a“center darted” or “center dart” fold pattern, since it results fromcreating, a dart or indentation (deformation) at or near an apex of eachflute, to be closed, with a follow-up step of folding. A pattern of foldsteps that accomplishes this is discussed below in connection with FIGS.7-24, and also in connection with FIGS. 28-47.

Herein, an end of a flute or corrugation will be characterized as closedby a “fold” or as being “folded” if it includes at least two creasestherein, each crease resulting in a portion of the media being foldedback on or over itself. The fold pattern in FIG. 15 has four suchcreases, discussed below. Preferred configurations include at least fourfolds or creases. The term “fold” is intended to be applicable, even if,when the media is folded back over itself, some structure or material,such as sealant, is positioned between adjacent layers of media.

II. The Folding Technique Described in U.S. Provisional Application60,395,009, filed Jul. 10, 2002 A. Overview of Process and ResultingDarted Flute

In FIG. 7, one example of a manufacturing process for making centerdarts is shown schematically at 60. In general, the non-corrugated sheet64 and the corrugated sheet 66 having flutes 68 are brought together toform a media web 71. The darting process occurs at station 70 to formcenter darted section 72 located mid-web. After the darting process, thez-filter media or Z-media 74 can be cut along the center darted section72 to create two pieces 76, 77 of Z-media 74, each of which has an edgewith a set of corrugations having folded ends.

Still referring to FIG. 7, it is noted that the process depictedgenerally involves formation of darts through folds occurring on amid-line 73 of an associated media web 71. Such a process will begenerally characterized herein as a “mid-web folding” or “mid-webdarting” process. This is to distinguish from an edge folding or edgedarting process, described below. Of course, the mid-web folding processshown in FIG. 7 is used to generate edge folds, once the web 71 is slitalong fold line 73.

The process of deforming the flutes 68, as part of generating a regularfold pattern, takes place at station 70. The folding process shown, ingeneral, involves inverting the ridges 80 of the flutes 68 and thenpressing (or folding) the inverted ridges 80 against the non-corrugatedsheet 64 to form the center darted section 72. In the embodiment shown,there are at least two rollers or wheels shown generally at 70 that areused to work the corrugated sheet 66. An indenting, inverting, ordarting wheel 84 operates first to deform or invert the ridges 80, whilea folder wheel 86 later presses or folds the inversions made by thedarting wheel 84 into the non-corrugated sheet 64 to form the dartedsection 72.

FIG. 7 also shows an optional manipulation to the corrugated sheet 66before encountering the darting wheel 86. The optional mediamanipulation includes engagement with a creaser wheel 88. The optionalcreaser wheel 88 engages the flutes 68 by initially nicking ortemporarily deforming by pressing inwardly the ridges 80 toward theuncorrugated sheet 64. This can help to start the process of deformationand to help the flutes 68 to be appropriately deformed (inverted) by thedarting wheel 86.

After engagement with the folder wheel 86, the step of cutting theZ-media 74 is shown. A splitter, blade or cutter is shown at 90 dividingthe Z-media 74 into pieces 76, 77.

Still in reference to FIG. 7, before the Z-media 74 is put through thedarting station 70, the Z-media 74 is formed. In the schematic shown inFIG. 7, this is done by passing a flat sheet of media 92 through a pairof corrugation rollers 94, 95. In the schematic shown in FIG. 7, theflat sheet of media 92 is unrolled from a roll 96, wound around tensionrollers 98, and then passed through a nip or bite 102 between thecorrugation rollers 94, 95. The corrugation rollers 94, 95 have teeth104 that will give the general desired shape of the corrugations afterthe flat sheet 92 passes through the nip 102. After passing through thenip 102, the flat sheet 92 becomes corrugated and is referenced at 66 asthe corrugated sheet. The corrugated sheet 66 is routed to the dartingprocess 70.

The type of corrugation provided to the corrugation media is a matter ofchoice, and will be dictated by the corrugation or corrugation teeth ofthe corrugation rollers 94, 95. A preferred corrugation pattern will bea regular curved wave pattern corrugation, of straight flutes, asdefined herein above. In some instances the techniques may be appliedwith curved wave patterns that are not “regular” and do not use straightflutes. A typical regular curved wave pattern used, would be one inwhich the distance D2, as defined above, in a corrugated pattern is atleast 1.2 times the distance D1 is defined above. In one preferredapplication, typically D2=1.25-1.35×D1.

Still in reference to FIG. 7, the process also shows the non-corrugatedsheet 64 being routed to the darting process station 70. Thenon-corrugated sheet 64 is depicted as being stored on a roll 106 andthen directed to the corrugated sheet 66 to form the Z-media 74. Thecorrugated sheet 66 and the non-corrugated sheet 64 are secured togetherat some point in the process, by adhesive or by other means (for exampleby sonic welding).

The process 60 shown in FIG. 7 can be used to create the center dartedsection 72. FIGS. 8-10 show one of the flutes 68 after initialdeformation; e.g., after engaging the indenting or darting wheel 84 andbefore engaging the folder wheel 86. The darting wheel 84 deforms aportion 69 of the ridge 80, by indenting or inverting it. By “inverting”and variants thereof, it is meant that the ridge 80 is indented orturned inward in a direction toward the non-corrugated sheet 64. FIG. 9is a cross-sectional view along the mid-point of the inversion 110created by the darting wheel 84. The inversion 110 is between a pair ofpeaks 112, 114 that are created as a result of the darting process. Thepeaks 112, 114 together form a flute double peak 116. The peaks 112, 114in the flute double peak 116 have a height that is shorter than theheight of the ridge 80 before inversion. FIG. 10 illustrates thecross-section of the flute 68 at a portion of the flute 68 that did notengage the darting wheel 84, and thus was not deformed. As can be seenin FIG. 10, that portion of the flute 68 retains its original corrugatedshape.

The particular process illustrated in FIGS. 7-24, is one of “centerindenting,” “center inverting,” “center darting” or “centerdeformation.” By the term “center” in this context, again, it is meantthat the indentation or inversion occurred at an apex or center of theassociated ridge 80, engaged by the indenting or darting wheel 84. Adeformation or indent will typically be considered herein to be a centerindent, as long as it occurs within 3 mm of the center of a ridge.

Again, herein the term “crease,” “fold,” or “fold line” are meant toindicate an edge formed by folding the media back on or over itself,with or without sealant or adhesive between portions of the media.

Attention is now directed to FIGS. 11-15. FIGS. 11-15 show sections ofthe darted section 72 after engagement with the folder wheel 86. FIG.15, in particular, shows an end view of the darted section 72, incross-section. A fold arrangement 118 can be seen to form a darted flute120 with four creases 121 a, 121 b, 121 c, 121 d. The fold arrangement118 includes a flat first layer 122 that is secured to thenon-corrugated sheet 64. A second layer 124 is shown pressed against theflat first layer 122. The second layer 124 is preferably formed fromfolding opposite outer ends 126, 127 of the first layer 122.

Still referring to FIG. 15, two of the folds or creases 121 a, 121 bwill generally be referred to herein as “upper, inwardly directed” foldsor creases. The term “upper” in this context is meant to indicate thatthe creases lie on an upper portion of the entire fold 120, when thefold 120 is viewed in the orientation of FIG. 15. The term “inwardlydirected” is meant to refer to the fact that the fold line or creaseline of each crease 121 a, 121 b, is directed toward the other.

In FIG. 15, creases 121 c, 121 d, will generally be referred to hereinas “lower, outwardly directed” creases. The term “lower” in this contextrefers to the fact that the creases 121 c, 121 d are not located on thetop as are creases 121 a, 121 b, in the orientation of FIG. 15. The term“outwardly directed” is meant to indicate that the fold lines of thecreases 121 c, 121 d are directed away from one another.

The terms “upper” and “lower” as used in this context are meantspecifically to refer to the fold 120, when viewed from the orientationof FIG. 15. That is, they are not meant to be otherwise indicative ofdirection when the fold 120 is oriented in an actual product for use.

Based upon these characterizations and review of FIG. 15, it can be seenthat a preferred regular fold arrangement 118 according to FIG. 15 inthis disclosure is one which includes at least two “upper, inwardlydirected, creases.” These inwardly directed creases are unique and helpprovide an overall arrangement at which the folding does not cause asignificant encroachment on adjacent flutes. These two creases result inpart from folding tips 112, 114, FIG. 9, toward one another.

A third layer 128 can also be seen pressed against the second layer 124.The third layer 128 is formed by folding from opposite inner ends 130,131 of the third layer 128. In certain preferred implementations, thenon-corrugated sheet 64 will be secured to the corrugated sheet 66 alongthe edge opposite from the fold arrangement 118.

Another way of viewing the fold arrangement 118 is in reference to thegeometry of alternating ridges 80 and troughs 82 of the corrugated sheet66. The first layer 122 includes the inverted ridge 110. The secondlayer 124 corresponds to the double peak 116 that is folded toward, andin preferred arrangements, folded against the inverted ridge 110. Itshould be noted that the inverted ridge 110 and the double peak 116,corresponding to the second layer 124, is outside of the troughs 82 onopposite sides of the ridge 80. In the example shown, there is also thethird layer 128, which extends from folded over ends 130, 131 of thedouble peak 116.

FIGS. 12-14 show the shape of the flute 68 at different sections. FIG.14 shows an undeformed section of the flute 68. The inversion 110 can beseen in FIGS. 12 and 13 extending along from where it engages thenon-corrugated sheet 64 (FIG. 15) to a point where it no longer exists(FIG. 14). In FIGS. 12 and 13, the inversion 110 is spaced at differentlengths from the non-corrugated sheet 64.

B. Specific Example From Provisional Application 60/395,009

FIG. 16 illustrates one embodiment of creaser wheel 88 that isoptionally used with the process 70. As can be seen in FIG. 7, whenused, the creaser wheel 88 is oriented such that its axis of rotation136 is oriented parallel to the flute direction. This means that thecreaser wheel 88 rotates in a plane that is in a direction transverse tothe flute length. In reference again to FIG. 16, the creaser wheel 88depicted is shown with its axis of rotation 136 passing centrallytherethrough. The creaser wheel 88 is generally tapered at oppositesurfaces 137, 138 from a central region 139 adjacent to the central axis136 extending to an end region 140. The end region 140 is narrow, whencompared to the width across the creaser wheel 88 at central region 139.In the example shown, the end region 140 is less than one-half the widthacross the creaser wheel 88 at the central region 139. In manyembodiments, the width across the end region 140 is less than one-thirdof the width across the central region 139. In the example embodimentillustrated, the tapered surfaces 137, 138 are tapered at an angle αless than 10°, at least 1°, and in the particular example, 3-6°.

The creaser wheel 88 is optionally used to initially nick the flute 68.In particular, the creaser wheel 88 rotates about the axis 136 in thedirection of movement of the corrugated sheet 66. The end region 140contacts the ridges 80 of the corrugated sheet 66 and presses the ridges80 in a direction toward the non-corrugated sheet 64. FIGS. 17-19 show across-section of the Z-media 74 after contact with the creaser wheel 88.A creaser indent is shown at 142. The ridge 80 can be seen to be pushedtoward the non-corrugated sheet 64 after contact with the end region 140of the creaser wheel 88. In FIG. 19, it can be seen that the indent 142may, in some instances, form a generally flat portion 144 extendingbetween opposite sides 146, 147 of the flute 68. Thus, in the exampleshown, the creaser wheel 88 flattens the ridge 80 toward thenon-corrugated sheet 64.

In typical preferred application of the techniques described, as theridge 80 is folded toward the non-corrugated sheet 64, it will also besealed to the non-corrugated sheet. One approach to accomplishing thissealing is through use of a sealant.

In FIGS. 17-19 an area of sealant 150 is shown. In an example process, abead of sealant 150 is applied between the non-corrugated sheet 64 andthe corrugated sheet 66 upstream of the creaser wheel 88. The indent 142is placed along a portion of the flute 68 that is above the area ofsealant 150. In other words, troughs 82 that are adjacent to the ridge80 that is put in contact with the creaser wheel 88 are secured to thenon-corrugated sheet 64 with the sealant 150.

Attention is next directed to FIGS. 20 and 21. One particular embodimentof an indenting or darting wheel 84 is shown at 160. The darting wheel160 shown includes a plurality of indentation picks or teeth 162extending radially from a surface 164 of the wheel 160. In the exampleembodiment shown, and in reference to FIG. 7, in general, the dartingwheel 84 rotates in a direction that is parallel to the flute direction.This means that the darting wheel 84 rotates in a plane that isgenerally transverse to the direction of the flutes.

Turning again to the example darting wheel 160 depicted in FIG. 20, theteeth 162 are preferably uniformly spaced about the radial surface 164.The teeth 162 are spaced to correspond to the particular geometry of thecorrugated sheet 66. That is, the spacing between adjacent ridges 80 ofthe corrugated sheet 66 is a primary factor in spacing between theadjacent teeth 162. The number of teeth 162 used is also a function ofthe diameter of the darting wheel 160. In the example shown, the dartingwheel 160 includes at least 50, no greater than 200, and typically100-150 teeth 162. In the specific example shown in FIG. 20, there are120 teeth 162. In a typical implementation, the darting wheel 160 has adiameter from the tip of one tooth 162 to another tooth 162 of at least8 inches (20.3 cm), no greater than 12 inches (30.5 cm), typically 9-10inches (22.9-25.4 cm), and in one example about 9.7 inches (24.6 cm).However, variation from this is possible.

In the embodiment shown, each of the teeth 162 has a crown 164 that issmooth and curved. The rounded shape to the crown 164 helps to deformthe flutes 68 without tearing the corrugated sheet 66. The radius of theteeth 162 may often typically be at least 0.005 inch (0.01 cm), nogreater than 2.0 inch (5.1 cm), typically 0.75-1.25 inch (1.9-3.2 cm),and preferably about 1.0 inch (2.54 cm). The thickness of each tooth isshown at dimension 168. The dimension 168, for the example shown, is atleast 0.01 inch (0.03 cm), no greater than 0.05 inch (0.13 cm), andtypically 0.02-0.04 inch (0.05-0.1 cm). The height of each tooth 162 isshown in FIG. 21 at dimension 170. The height 170, in someimplementations, is at least 0.05 inch (0.13 cm), no greater than 0.5inch (1.3 cm), and typically 0.1-0.3 inch (0.25-0.76 cm).

Each tooth 162 has a pair of sides 171, 172, between which the crown 164extends. The length of the tooth 162 between the sides 170, 171 is atleast 0.2 inch (0.5 cm), no greater than 1 inch (2.54 cm), and typically0.5-0.7 inch (1.3-1.8 cm).

In FIG. 22, the darting wheel 160 is shown located between a pair offluted rollers 176, 178. The fluted rollers 176, 178 are, in someinstances, driven by the movement of the corrugated sheet 66 along theprocess 70. The fluted rollers 176, 178 help to keep the darting wheel160 on-center with the flutes 68. As can seen in FIG. 22, the flutedrollers 176, 178 include flutes or corrugations 180 that will mesh withthe corrugated sheet 66. FIG. 22 shows the rollers 176, 178 onlypartially corrugated. It should be understood that, in practice, therollers 176, 178 are often fully corrugated.

In reference again to FIGS. 8-10, these figures illustrate one of theflutes 68 after engaging the darting wheel 84, for example, the dartingwheel 160. In processes wherein the sealant bead 150 is applied upstreamof the darting wheel 84, after contact with the darting wheel 84, theridge 80 forms inversion 110 to extend toward and to touch or engage thesealant bead 150. This helps to hold the inversion 110 and the doublepeak 116 in place for the folder wheel 86. In FIG. 9, the inversion 110is shown in engagement with the sealant bead 150 but not in engagementwith the non-corrugated sheet 64. In some implementations, the inversion110 can be pushed fully through the sealant bead 150 into touchingengagement with the non-corrugated sheet 64.

FIGS. 23 and 24 illustrate one example of folder wheel 86. The exampleof the folder wheel 86 in FIGS. 14 and 15 is depicted at 185. The folderwheel 185 functions to press the flute double peak 116 against thenon-corrugated media 64 and against the inversion 110 to form dartedsection 72.

In reference again to FIG. 7, the folder wheel 86 rotates about acentral axis 188 that is generally parallel to the direction of theflutes 68. As such, the folding wheel 86 rotates in the same generalplane as creaser wheel 88 (if used) and darting wheel 84; that is,folding wheel 86 rotates in a plane that is generally transverse to thedirection of the flutes 68.

In reference again to FIGS. 23 and 24, the folder wheel 185 has asmooth, blunt surface 190 for engaging the corrugated sheet 66. Thesurface 190, in example embodiments, is a toroidal surface on a radius Rof at least 1 inch (2.54 cm), no greater than 3 inches (7.6 cm), andtypically 1.5-2.5 inches (3.8-6.4 cm).

The folder wheel 185 has opposite axial surfaces 192, 194. The distancebetween the axial surfaces 192 and 194 generally defines the thicknessof the folder wheel 185. In example embodiments, this thickness is atleast 0.1 inch (0.25 cm), no greater than 0.5 inch (1.3 cm), andtypically 0.2-0.4 inch (0.5-1.0 cm). The diameter of the example folderwheel 185 is at least 3 inches (7.6 cm), no greater than 10 inches (25.4cm), and typically 5-7 inches (12.7-17.8 cm). The surfaces between eachof the axial surfaces 192, 194 and the blunt surface 190 is curved, andin the illustrated embodiment, is on a radius r of at least 0.02 inch(0.05 cm), no greater than 0.25 inch (0.6 cm), and typically 0.08-0.15inch (0.2-0.4 cm).

C. Example Media Section and Elements

FIG. 25 illustrates a perspective, schematic view of z-media 74 afterbeing modified by indenting and folding to include the darted section72, and after being separated into pieces 76, 77 by the cutter 90, FIG.7. The folded flutes 120 can be seen at the downstream edge 196. The airto be cleaned flows in at the upstream edge 198 as shown at arrows 199.The air flows through the Z-media 74 at the upstream edge 198, throughthe media, and then exits in the region 200 between the darted (folded)flutes 120 and the non-corrugated sheet 64.

FIGS. 26 and 27 illustrate example filter elements utilizing Z-media 74having folded flutes 120. In FIG. 26, the Z-media 74 with the foldedflutes 120 is wound into filter element 202. The filter element 202includes opposite flow faces 203, 204 that, in this instance, areparallel. In alternate configurations, one of the flow faces 203 or 204may not lie in a single plane, e.g., it may be conical. An example of aconically shaped filter element with z-media is shown in U.S. Des.399,944; U.S. Des. 428,128; and U.S. Des. 396,098 and z-media withfolded flutes can be configured analogously. The flow face 203 is shownschematically, with only portions showing end flutes 205, but it shouldbe understood that the entire filter face 203 will typically have endflutes 205. In use, fluid to be filtered enters the upstream flow face(in this instance 204) and exits downstream flow face, in this instance,203). The fluid generally flows in the same direction entering theupstream flow face 204 as it exits the downstream flow face 203. Again,this configuration generally referred to herein as a “straight throughflow” filter.

As can be seen in FIG. 26, the particular filter element 202 is round,in that it has a circular cross-section. When using the filter element202 in an air cleaner system, the filter element 202 may be modified byplacing an appropriate gasket or other type of sealing members thereon.One example sealing gasket 208 is shown secured to an outer cylindricalsurface 209 of the element 202. The sealing gasket 208 shown includesfoamed polyurethane and forms a seal with a housing by compression ofthe gasket 208 against the housing. Examples of usable sealing gasketsinclude the ones described in U.S. Pat. No. 6,190,432 and U.S. patentapplication Ser. No. 09/875,844, filed Jun. 6, 2001, and commonlyassigned hereto.

FIG. 27 illustrates another example of a filter element 216 utilizingz-media 74 and wound into the filter element 216. As with the filterelement 202 shown in FIG. 26, the filter element 216 has opposite flowfaces 217, 218 to accommodate straight through gas flow. As with theFIG. 26 embodiment, this embodiment also shows the flow face 217schematically, with only portions showing end flutes, but it should beunderstood that the entire filter face 217 typically will show the endflutes. In this embodiment, the filter element 216 is obround.Specifically, this particular filter element 216 has a cross-section inthe shape of two parallel sides 219, 220 joined at their ends by curvedportions 221,222. The filter element 216 may include appropriate sealingmembers or gaskets, and in the example shown, includes the type ofsealing member 224 described in U.S. Pat. No. 6,190,432. This sealingmember 224 includes polyurethane molded on a frame, secured to theelement 216. In each of the elements 202, 216, a central core 226, 227is shown as having the z-media 74 wound therearound. In someembodiments, the filter elements 202, 216 can be coreless. By“coreless,” it is meant that the elements are absent a central mandrel,tube, stick, or other piece that the z-media 74 is wound around.

D. Example System

The filter media described herein can be made into elements, of whichexamples are shown in FIGS. 26 and 27. The filter elements are useablein fluid (liquid or air) cleaners. One such system is depictedschematically in FIG. 27A generally at 230. In FIG. 27A, equipment 232,such as a vehicle, having an engine 233, with some defined rated airflow demand, for example, at least 300 cfm, for example 500-1200 cfm, isshown schematically. Equipment 232 can include a bus, anover-the-highway truck, an off-road vehicle, a tractor, or marineequipment such as a powerboat. The engine 233 powers the equipment 232,through the use of an air and fuel mixture. In FIG. 27A, the air flow isshown drawn into the engine 232 at an intake region 235. An optionalturbo 236 is shown in phantom, as optionally boosting the air intakeinto the engine 233. An air cleaner 240 having a filter construction 242is upstream of the engine 232 and the turbo 236. In general, inoperation, air is drawn in at arrow 244 into the air cleaner 240 andthrough the primary element 242. There, particles and contaminants areremoved from the air. The cleaned air flows downstream at arrow 246 intothe intake 235. From there, the air flows into the engine 233 to powerthe equipment 232.

Other examples of useable systems include intake air filters gas turbinesystems. Of course the media can also be used in liquid (for example oil(lubrication), fuel or hydraulic) filters.

III. Selected Improved Techniques for Generating Folds in CorrugatedMedia

The techniques described in U.S. provisional application 60/395,009, canbe used to form a regularly folded or regular fold pattern, to generatefolds, darts or regular gathers at the ends of selected flutes of flutedor corrugated media (especially regular, curved wave pattern corrugatedmedia) in a discontinuous or a continuous process. However with acontinuous process, especially as line speed increases, for example atrates from about 30 meters per minute on up, the flexible nature of thecorrugated media makes quality control for generation of the regularfold, increasingly difficult. While this in part due to timing issueswith respect to the conduct of the deformation step, conducted with thedarting or indentation wheel 84, FIG. 7, it is also a function of theflexible nature of the media and a difficulty of ensuring that theindent or dart is not only centered at or near the apex of thecorrugation media, but that the corrugation shape itself does not leanin either the upstream or the downstream (machine) direction. Improvedtechniques that address these issues are described in this section.

A. General Principles

Referring again to FIG. 6, and in particular to corrugation 53, ingeneral surface 53 a of a ridge 53, (in this instance directed away fromthe non-corrugated sheet 44) will sometimes be referred to as the“outside” surface of the ridge 53; and, opposite surface 53 b, which isin the trough of corrugation 53 (and in this instance faces sheet 44)will sometimes be referred to as the “inside” surface of the corrugation53. In general, a folding or darting step for a center darting of thetype described above, involves deformation or indentation (in a portionof a ridge 53) directed inwardly; i.e., from the outside surface 53 atoward the inside surface 53 b. When the corrugated sheet 43 is securedto a noncorrugated sheet 44, the indentation will in many instances betoward flat sheet 44 such that, eventually, a portion of surface 53 bengages the flat sheet 44 (or sealant on the flat sheet 44). Forexample, such an approach was described above to provide the structureof FIG. 15. However, alternatives, for example as described below inconnection with FIG. 48 are possible.

For certain of the folding techniques generally characterized herein, astep in the folding process is providing a deformation (in the instanceof FIG. 15 an indentation) in outside surface 53 a, FIG. 6, by directinga pin arrangement or similar construction against surface 53 a in thegeneral direction of arrow 55, FIG. 6. This type of deformation step hasgenerally been referred to as an “indentation step” or “darting step,”as explained above in connection with FIG. 7 and wheel or roller 84.

In general, two techniques have been found useful to facilitategeneration of a regular fold in corrugated media. These two techniquesare:

-   -   1. Preferred supporting and containing a flute of the flexible        corrugation material, during the deformation process; and    -   2. Utilization of a moveable (retractable/projectable) tooth or        indentation pin arrangement, timed to project outwardly at a        selected time and location, to provide a preferred deformation        (preferably an indent or initial dart).

A variety of techniques can be utilized to accomplish these preferredprocesses. For example, containment and support can be provided bysupporting the flute or corrugation (during deformation) from: (a) alocation outside the corrugation (flute); (b) a location inside thecorrugation (flute); or (c) both. The latter approach, in which thecorrugation (flute) is supported on both the inside and the outsideduring the deformation process, will generally be referred to herein asan encapsulation approach, or by variants thereof.

Schematic depictions of examples of each of these three approaches areillustrated in FIGS. 28-30. In FIG. 28, an approach is shown in whichthe support is provided along a same side (outside) of a corrugation tobe folded closed, as a side against which the indenter dart orindentation pin arrangement will press, with the support providedimmediately adjacent opposite sides of the indentation pin arrangement.In FIG. 29, an approach is shown in which support is provided on a side(inside) of the corrugation opposite from that against which theindentation pin arrangement will press to start the deformation, againwith support provided adjacent opposite sides of the indentation pinarrangement. Finally, in FIG. 30 an encapsulation process is shown, inwhich support for the corrugation to be folded is provided both insideand outside of the corrugation, in each instance adjacent opposite sidesof the indentation pin arrangement.

Herein in the context of the previous paragraph, the term “adjacentopposite sides of the indentation pin arrangement” and variants thereof,is meant to refer to the location of the support relative to where theindentation pin arrangement engages the corrugation to cause inversion.The term is meant to indicate that the support is locatedlongitudinally, along the length of longitudinal extension of thecorrugation, at least at the same longitudinal location as the locationat which the indentation pin arrangement contacts the corrugation,except offset to the side of the corrugation location (typically ridge)where indentation contact occurs. This will sometimes be referenced asbeing indenting a corrugation that is supported at a regionlongitudinally adjacent where indentation will occur. This will beapparent from the detailed descriptions below. In FIG. 28 regions395,396, indicate this type of support. It is in contrast to thearrangement of FIG. 7, in which there was either no support to thecorrugation at all, or any support to the corrugation was locatedspaced, longitudinally,.along the length of the corrugation, away fromthe darting pin or indentation pin contact location.

Referring to FIG. 28, reference numeral 370 generally indicates thefluted or corrugated media. In the instance of FIG. 28, the corrugatedmedia 370 has a regular, curved, wave pattern for the corrugation 371,with straight flutes. Although the techniques described herein wereparticularly developed for managing such corrugations, the techniquesdescribed herein are not specifically limited to such applications,unless otherwise stated.

In FIG. 28, a particular corrugation 371 to be folded is indicated. Ingeneral, the initial folding step is conducted by a deformation orindentation pin arrangement (not shown) applied in the general directionof arrow 375 to an outside or convex side 376 (from the viewpoint of thearrow 375) to form an indent or deformation. For the particularembodiment shown, the deformation pin is directed against the convexside (outside) 376 of the corrugation 371 in such a manner that: thecorrugation 371 is first engaged by the pin arrangement at or along anapex 376 a; and, such that the indentation force applied by thedeformation pin arrangement is generally directed in a direction normalor orthogonal to a plane 377 a defined by troughs 377 on opposite sidesof apex 376 a. It is noted, however, that variations from this, arepossible.

Referring still to FIG. 28, corrugation 371 is supported and contained,for the darting process, by form 380. The form 380 is depicted inphantom, in FIG. 28. Form 380 is generally and preferably configured tohave a corrugated portion 381 configured to have a surface 382 generallydefined as an inverse of the convex or outside surface 371 a (ofcorrugation 371). Thus, the form 380 is preferably configured to mate ormesh with the corrugations of the media. Although a perfect mesh or mateis not required, it will be preferred to have as much engagement aspossible, to provide maximum support. The form 380 is preferably rigid,not flexible like the media of the corrugation 371. The form 380, forexample, may comprise metal or a hard plastic.

Further, form 380 includes gap 383 therein, through which the darting orindentation pin arrangement can project, in the direction of arrow 375,to engage corrugation 371. Preferably gap 383 is positioned aligned witha portion of ridge 376 a.

When it is said that the corrugation is “supported and contained”, forthe outside darting process, it is meant that during the indentation ordarting process, the indentation or darting pin projects adjacent thesupport so that the corrugation is supported, along its longitudinallength, at the same longitudinal location as the darting occurs, butoffset to the side. Corrugation support which occurs immediately onopposite sides of, or adjacent, the indentation pin, as characterizedabove, would be a specific form of indentation which occurs in acorrugation that is supported and contained for the darting process. Inparticular, it would be a form in which there is support on both “sides”of the indentation pin, as the indentation pin projects through a gap inthe support. The term “sides” in the previous sentence meaning in thedirections of double headed arrow 384, FIG. 28, from gap 383.

With the construction shown, when the darting pin arrangement isdirected through gap 383 in the direction of arrow 375 against outsidesurface 371 a of corrugation 371 (and when form 380 is present as shownin FIG. 28), the flexible media 370 in the region of corrugation 371 iscontained between points 388 and 390, against deformation either in thedirection of arrow 391 or in the direction arrow 392. This will helpensure that the flexible corrugated media 370 is contained and does notdeform undesirably, during the indentation step. Again, the support isprovided, in part, at regions 395,396.

In general, a corrugation will be considered “supported and/orcontained” by a support form 380, if either: (a) the form 380 containsthe corrugation by contact with the corrugation at or near troughs 377on opposite sides of the corrugation; or (b) the form 380 extends overthe corrugation to cover a distance of the height (H1 of FIG. 6) of thecorrugation which is at least 10% of the height (H1); or (c) both.Typically both are used and the extension will be at least 20% of theheight (H1), preferably at least 30% of the height (H1), most preferablyat least 90% (for example 100%) of the height (H1). That is, if surface381 of form 380, FIG. 28, extends from apex 376 a downwardly towardplane 377 a a distance of at least 10% of H1, the corrugation will beconsidered supported by the form 380. Again, typically the height orextent of support, in the direction of H1, will be at least 90% of H1,typically 100% of H1.

A variety of techniques and configurations can be used to define andprovide form 380. A particular approach, usable with continuousmanufacturing processes, is described herein below, especially inconnection with FIG. 36.

Attention is now directed to FIG. 29. In FIG. 29, a corrugated (fluted)sheet 400 is depicted. Corrugated (fluted) sheet 400 comprises aregular, curved, wave pattern corrugation 401 of straight flutes. InFIG. 29 a particular corrugation or flute 405 is depicted, to be foldedin a folding process initiated with an indentation pin arrangementdirected toward convex (outside) surface 407, for example at apex 407 a,under force in the general direction of arrow 408.

For the particular arrangement shown in FIG. 29, the indentation pinarrangement is directed toward an apex 407 a of the convex surface 407,in the direction of arrow 408 with force directed generally normal to,or orthogonal to, a plane 409 defined by troughs 410, on opposite sidesof the corrugation 405. Variations from this, however, are possible.

Corrugation 405 is shown supported inside (i.e. along a concave surface411) by form 412. Form 412 includes a central recessed region 413therein, to receive a depression or indent in corrugation 405 from theindentation pin arrangement. Form 412 also includes sides 414 and 415generally defined to conform with a shape of corrugation 405 in regions405 a and 405 b, respectively. As with the arrangement in FIG. 28, theform or support 412 of FIG. 29 will generally keep the flexible media400 centered with respect to an indentation pin arrangement directedthereagainst. The form 412, of course, is preferably constructed from arigid material.

Herein, a corrugation will be considered supported along the inside aslong as the support form along the inside extends, from plane 409 towardapex 407 a, at least 10% of the peak height (H1 of FIG. 29). Typicallythe inside support will extend at least 20%, preferably at least 30%, ofH1. A typical example would be 40%-60% of H1.

As with the embodiment of FIG. 28, for the form 412 to be considered tosupport the corrugation 405, it is not required that the form 412 havean outer surface along sides 414, 415, which has a shape in perfectmatch to the corrugation shape at these locations. However aconfiguration as close as possible to a matching shape, is preferred.

Also as with FIG. 28, the support in FIG. 29 is at least is at regions416, 417, longitudinally adjacent where indentation will occur.

Attention is now directed to FIG. 30. In FIG. 30 an extension ofcorrugated media 430 is depicted. The corrugated media 430 shown isgenerally a regular, curved, continuous wave pattern corrugationarrangement 431 with straight flutes. Corrugation 435 is shownpositioned for a folding process to be initiated, by an indentation pinarrangement directed against convex surface 437 of corrugation 435 inthe direction of arrow 438. In FIG. 30, corrugation 435 is shownencapsulated, between outside or outer form 440, shown in phantom,supporting outside 435 a, which generally corresponds to form 380, FIG.28; and, inner form 441 (against inside surface 435 b), which generallycorresponds to form 412, FIG. 29. The term “encapsulated” and variantsthereof, when used in this context, is meant to refer to a corrugationsuch as corrugation 435, which is contained along both the convex(outside) and the concave (inside) surfaces, in the vicinity of theindentation pin (preferably on opposite sides of the indentation pinarrangement or darting pin at the same longitudinal location along thelength of the corrugation 435) during indentation pin arrangement (ordarting pin) projection into the media. Similarly to the embodiments ofFIGS. 28 and 29, as a result of the containment, in this particularinstance by encapsulation, the corrugation 435 will remain centered andwill not undesirably move during the initiation of the folding process.

In an arrangement in which the length D2 (FIG. 6) of the corrugation isapproximately 1.2-1.4 times D1, it may be convenient to utilize as theindentation pin arrangement, a single indentation or darting pindirected against the apex of the corrugation, with the pin being on theorder of 0.7-0.8 mm thick, and on the order of 5 mm to 40 mm wide. Onthe other hand, when the length D2 is greater than about 1.4 times D1,it may be desirable to either use a wider indentation pin arrangement,or multiple indentation pin blades, to accomplish the desiredindentation step of the folding process.

In many manufacturing applications, it will be preferred to fold thecorrugated media after it has been tacked or otherwise secured to thenon-corrugated media. In Section II above, an example of darting orfolding process was shown, with such a combination, that was conductedat a location spaced from the edges of the media, and located generallycentrally along a continuous web of corrugated media attached tonon-corrugated media. Such an approach was characterized as mid-webfolding and as leading to formation of edge darting, by slitting theresulting folded or darted combination, down the center of the dart. Anapplication of this technique but using outside support for the flutesduring indentation is illustrated herein schematically in FIG. 31.

Referring to FIG. 31, a schematic depiction of a typical manufacturingprocess is shown. In general, a corrugating station is shown at 500,with two corrugated rollers 501, 502 positioned to form a corrugatingbite 503 therebetween. A non-corrugated media sheet 506 is showndirected into the bite 503 to be corrugated with a resulting continuouscorrugated web 507 having corrugations 508 thereacross in a directiongenerally perpendicular to the machine direction 509 being shown. Anon-corrugated sheet 515 is shown being brought into engagement withside 516 of corrugated sheet 507. Typically, the two sheets 507, 515will be tacked to one another at various points there along, tofacilitate the manufacturing process. To accomplish this tacking anadhesive, typically a hot melt, can be used. In some instances sonicwelding can be used to effect the tacking.

In some applications, an adhesive bead, hot melt, or sealant strip 525is positioned between the two sheets 507, 515, in a central location.The sealant of the sealant strip is used to ensure a seal, at thelocation of the fold, in the final product. In the alternative, othersealing techniques such as sonic welds may be useable. The sealant strip525 can be applied to continuous sheet 506, before it is corrugated onside 516. If it is applied to continuous sheet 506, before it iscorrugated, in general the relevant surface portion of one of thecorrugating rollers 501, 502 would preferably have a gap therein toaccommodate the sealant bead. In the instance of FIG. 31, the gap (notviewable) would be in roller 502. An advantage to this approach would bethat the sealant bead will follow the corrugations 508 in the corrugatedmaterial. As a result, the sealant will be more appropriately locatedinside of the folds or creases, after processing. This means that arelatively secure closed fold will result, with less sealant used, thanwould typically be required for an approach in which sealant is firstapplied to the non-corrugated sheet, for example as shown optionally at525 a, before the non-corrugated sheet and the corrugated sheet arebrought together.

In a step (shown at indentation station 530) a deformation (orindentation or darting) pin arrangement, in this instance comprising awheel 531, is directed into the convex side of each corrugation 508 onside 507 a of corrugated sheet 507. At this location, an upper form 540for supporting (outside support) of each corrugation during theindentation process is provided. Support to the webs 507 and 515underneath, is provided by rollers 541, 542.

In the machine direction, media web next proceeds to a pressing/foldingstation 550, at which sides resulting from the initial indentationprocess are folded over toward one another, to form the four crease foldshown in FIG. 15. At pressing/folding station 550, a press is used (tocause a center folded strip section 570), which will make a press stripthat is at least 1 mm wide, typically 4 mm to 40 mm wide in theresulting media construction 571. The pressing station 550 can comprisea wheel 572, with a cross-section generally analogous to that shown forwheel 185, Figs. 23 and 24, except dimensioned in width to cause a presswidth as indicated above. At cutting station 580, the media 571 is shownslit down strip 570. This will result in two extensions 581, 582 ofmedia 583, each of which has an end respectively terminating in folds,for each convex flute (relative to the flat sheet) with ends similar toend or fold arrangement 118, FIG. 15.

Of course, folded flutes could be made at an edge (for example one ormore of edges 595, 596), instead of along a center portion of thecorrugated media, using a similar approach. In this latter instance, nofinal step of slitting would necessarily be required, unless trimmingwas considered preferable to remove excess sealant or media.

In some instances, it may be possible to apply the initial indentationpressure asymmetrically to the corrugation, i.e., not directed againstan apex to cause a symmetrical fold.

In general, when it is desired to apply a mid-web folding process (tofold corrugated media that is already secured to non-corrugated media),by an initial indentation or darting pin projection against an exposedconvex surface of an individual corrugation and toward a non-corrugatedmedia, an outer support approach (analogous to FIG. 28) will bepreferred. This is because it would be difficult to provide corrugationsupport along an inner surface, between the flat sheet and thecorrugated sheet, especially along a center portion of a corrugatedsheet/flat sheet combination.

B. An Approach to Supported Indentation with an Outer Support; FIGS.32-40.

Outside support to a corrugation, during an indentation step, can beprovided in practice, by a variety of arrangements. In FIG. 32-40, asupport arrangement is shown, which utilizes a rotating roller or wheel.In FIG. 32, the roller or wheel is indicated generally at referencenumeral 650, in perspective view. In FIG. 33, the roller wheel 650 isshown in side elevational view. In FIG. 34, a portion of roller or wheel650 is shown in enlarged view. FIG. 35 is a fragmented, schematic,cross-section of roller or wheel 650, taken generally along line 35-35,FIG. 34. In FIG. 36 a schematic view showing an indentation step, usingan indentation pin arrangement 652 is shown. In FIG. 36 a, an enlargedportion of FIG. 36 is depicted. In FIGS. 37 and 38, a darting orindentation pin projection is shown. In FIGS. 39-40, an internal camcomponent is shown.

Referring first to FIG. 32, wheel 650 is an outside support wheel 655for corrugations, during an indentation step of a corrugation foldingprocess. In addition, wheel 650 includes a projectable/retractableindentation pin arrangement 652, not viewable in FIG. 32, to provide foran initial indentation step into a corrugation, during a portion of afolding process. This will be discussed below, in connection with thedescriptions of FIGS. 36 and 36 a.

Still referring to FIG. 32, in general the wheel 650 includes an outer,annular, corrugation engagement surface 657, depicted enlarged in FIG.34. Referring to FIG. 34, the outer corrugation engagement surface 657comprises a plurality of alternating ridges 658 and troughs 659 sizedand configured, to engage an outside surface of a corrugated material.Preferably the ridges 658 and troughs 659 are configured to define aregular, curved, wave pattern of straight ridges and troughs,corresponding to the corrugation pattern of the media to be folded,except surface 657 is positioned around the outside of a wheel 650, andthus the corrugations 658 and troughs 659 have a slight radius to theirextension, not present in the corrugated media when the media isflattened out, as shown in FIG. 31.

Referring to FIG. 32, a bottom 661 of each trough 659 includes, in acentral portion 662 thereof, a slot 663. The slot 663 is sized andpositioned so that an indentation pin arrangement 652, not shown in FIG.32, can selectively be projected through the slot 663, in a directionaway from a center axis 664 of the wheel 650 (or toward media), to causean indentation in a selected, supported, corrugation during use. (Alsothe indentation pin arrangement 652 can be retracted through slot 663toward axis 664.)

Still referring to FIG. 32, for the particular embodiment shown, thewheel 650 is mounted on a rotation bearing 665. Preferably the wheel 650is mounted such that its rotation will be driven by the corrugated mediain use. That is, preferably wheel 650 is not driven during use, exceptthrough engagement with the corrugated media to be folded, FIG. 31.

Still referring to FIG. 32, preferably each ridge 658 and trough 659 hasan end extension 668, 669 at opposite ends of each slot 663 ofsufficient length, to support the corrugation to be deformed at oppositeends of the slot 663, during an indentation process. Preferably thelength of each extension 668, 669 is at least 6 mm., and typically atleast 12 mm. Typically, each slot 663 will have a length of at least 6mm., typically at least 12 mm.; and a width of at least 0.5 mm.,typically at least 0.7 mm.

In general, the indentation pin arrangement 652 will include a pinprojection/retraction mechanism constructed and arranged to selectivelydrive or project an indentation or darting pin arrangements through oneof slots 663 against or into an engaged corrugation to be folded, and toselectively retract an indentation pin arrangement when appropriate.This process can be understood, by consideration of the embodimentdepicted in FIGS. 36-40.

Referring to FIG. 36, wheel 650 is shown schematically, in engagementwith corrugated media 672. In particular, corrugation 673 is shownsupported by trough 674 of wheel 650; see fragmentary enlargement FIG.36A. Trough 674 is a particular one of the troughs 659 and thus includesa slot corresponding to slot 663, FIG. 32, in a central portion thereof.

Referring to FIG. 36A, indentation pin arrangement 677 is shown driventhrough slot 678 in a radially outward direction from surface 657, andaxis 664 (FIG. 36), into supported corrugation 673. As a result, anindentation corresponding to the indentation shown in FIG. 9, incross-section, is initiated. (It is noted than in FIGS. 9 and 36A, theindentation is shown to be sufficiently long (or deep) to cause theindent 679 to connect the non-corrugated sheet 680. While this ispreferred, it is not required in all applications.)

The indentation pin arrangement 652, including indentation pin 677, ispreferably arranged such that projection of the pin 677 outwardlythrough slot 663, FIG. 36A, is: (a) at its maximum extent of projectionat indentation formation position 681; i.e., when the pin 677 isapproximately orthogonal to a plane defined by sheet 680 or as generallydefined by troughs 682, 683 on opposite sides of the corrugation 673;and (b) so that the pin 677 is completely retracted out of engagementwith the corrugation 673 when the media is not supported, for example ata rotation angle A (FIG. 36) of no more than 2 times (2×) the pitch inthe upstream direction, preferably no more than 1 time (1×) the pitch inthe upstream direction. In this context, reference to the “upstreamdirection”, is meant to a direction from which the web 684 is fed intothe roller 650. In the instance of FIG. 36, the web generally moves inthe direction of arrow 685. Thus, the upstream side is indicated at 686and the downstream side is indicated at 687, for the web 684. Therotation angle A would be defined as an angle extending clockwise fromthe center line or indentation formation position 681. It is noted thatfor the arrangement shown in FIG. 36, during operation roller 650 wouldrotate counterclockwise, i.e. in the general direction of arrow 688. Ofcourse the process could be configured for a reverse rotation andmachine direction.

It is generally preferred that the pin arrangement 652 (FIG. 36A) beunder projection movement radially outwardly when it engages the apex ofan engaged corrugation plane. This is facilitated by relatively smallangle A, since a small angle A helps to provide that the pin is actuallybeing forced radially outwardly from axis 664, toward and intoengagement with the corrugation 673, while the corrugation 673 issupported. This is shown at locations 681 and 681 a, in FIG. 36A.

A variety of arrangements can be used to project and retract theindentation pin 677. A particular pin projection/retraction arrangement690.is depicted in FIGS. 35-40. It uses a plurality of spring loadedpins 677, one associated with each slot 663. Referring to FIGS. 37 and38 a pin 677 is shown in its entirety. The pin 677 includes a projectionportion 692, which is configured to pass through slot 674 with tip 693directed toward a corrugation, in use. The projection portion 692 (FIG.37) includes beveled ends 694, 695, for a preferred indentation ordeformation. Edge 696 (FIG. 38) can be rounded or beveled, to facilitateindentation without damage to the media.

The tip 693 is mounted on projection support 697, in extension outwardfrom base 698. The base 698 extends between end portions 699, 700, witheach end 699, 700 including a spring receiving trough 701 therein.

Base 698 includes, opposite projection support 697, a surface 703 foruse, as described below.

Referring to FIG. 35, a schematic depiction, an individual pin 677 isshown mounted by first and second circular springs 705, 706, to bebiased in the direction of arrow 707 within wheel 650. As a result, eachpin 677 will rotate with wheel 650 around bearing 665, FIG. 32, in linewith (and in coordination with) its associated slot 663.

In order to project selected pins 677 outwardly through slots 663, atthe appropriate time, the wheel 650 is mounted to rotate around astationary, circular cam 711, FIG. 35. By the term “stationary” in thiscontext, it is meant that the cam 711 does not rotate with wheel 650 inuse.

Referring to FIG. 39, outer annular surface 712 of cam 711, includes aportion 712 which extends (counterclockwise in FIG. 39) between points713 and 714 of circular, stationary, cam 711 and is appropriatelyrecessed, relative to the wheel 650, such that pins 677 passing thereover, are completely retracted. On the other hand, surface portion 716in extension counterclockwise between points 717 and 718 operates as acam surface which, when engaged by surface 703 of each pin 677, willforce the pin 677 to project outwardly through slot 663, an appropriateextent to cause desired indentation, usually an extent of projection onthe order of 50%-100% of the flute height.

Referring to FIG. 39, movement of the pin 677 (FIG. 36) from a mostretracted position to a most projecting position, occurs the pin engagescam ramp 720. The cam ramp 720 is preferably configured to cause anamount of projection of an associated pin outwardly of at least 50%-100%of the flute height over a preferred rotation angle (angle A) aspreviously described for 36. The reason for this is that it causes asubstantial projection effect of the pin, against an associatedcorrugation in a web, during indenting or darting while the corrugationis supported.

Cam ramp 721 allows for pin retraction.

It is noted that in the schemation of FIG. 35, the slot 663 behindregions 722 of wheel 650, into which the base 698 of pin 677 will move,during projection, is not viewable. Also, typically springs 705, 706 arecontinuous and all pins 677 are mounted on the same pair of springs 705,706 to be biased against shelves 723 in wheel 650 until cam ramp 720(FIG. 39) on cam wheel 711 is reached.

In FIG. 36 a smooth roller 725, for back up support to pressure exertedn web 684 by roller 650, is shown.

C. An Approach to Supported Indentation within an Inner Support; FIGS.4145.

Attention is now directed to FIGS. 41-45, in which an arrangement forproviding inside support to a corrugation, during an indentationprocess, is shown. Referring to FIG. 41, an inside support 730 isdepicted. Inside support 730, generally comprises a rotatable roller orwheel 731 (or receiver roller or wheel), mounted to rotate around axis731 a, on a bearing, not shown. The wheel 731 has an outer annularsurface 732 configured to provide support to the inside of acorrugation, during an indentation process.

Attention is directed to the side elevational view of wheel 731 shown inFIG. 42. Surface 732 can be viewed to comprise a series of troughs 734,configured to receive media troughs (or inverted ridges) on oppositesides of a corrugation ridge to be indented. Between each pair oftroughs 734 is provided an indentation support 736 which preferablycomprises opposite, radially outwardly projecting side projections 737,738 and a recessed center 739.

A portion of wheel 731 is depicted in enlarged view, in FIG. 43. Theterm “recessed” when used in connection with defining center 739, ismeant to indicate that a bottom 739 a of the recessed center 739 ispreferably recessed in the direction of, but not necessarily as far as,bottoms 734 a of the troughs 734.

In the embodiment of FIG. 43, each center 739 is recessed the sameamount of the troughs 734. Typically and preferably each recessed center739 has a bottom 739 a which, in the cross-section shown in FIG. 43, hasa radius about the same as the media thickness plus 0.5× the indentionpin thickness.

In general, the surface definition of troughs 734 and sides 737, 738 isselected to correspond with corrugated media to be supported, during anindentation process. Partially recessed center 739 is generally sized toreceive a projecting portion of an indentation pin arrangement, and acorresponding inverted or indented tip of corrugation media, during anindentation process. An example of this is shown in FIGS. 44 and 45.

Of course the recess center 739 should be sized to allow for room of thethickness of the media (twice) and the thickness of the indenting pin,during an indentation or deformation process. In this manner, the mediawill not likely be torn or substantially damaged, during the insidesupport deformation or indentation process.

In general, wheel 731, FIG. 44, would be mounted on a bearing, in atypical process, to be rotated or driven by the corrugated media 740 asopposed to being independently driven. This will help ensure that theengaged and supported corrugations in the media are centrallypositioned. In FIG. 44, the direction of movement of the media 740 isindicated at arrow 741, and the direction of rotation of wheel 731 byarrow 742.

Referring to FIG. 45, web 740 is shown being indented at 752, withinside support provided by roller 731. The web direction is indicated atarrow 741. The direction of indentation is shown at arrows 754.

Of course the indentation pin used with an inside support analogous toinside support 730, may be positioned on a wheel analogous to wheel 650,FIG. 32, if desired. When this is the case, as shown in FIG. 46, theprocess would be an encapsulation process for the corrugated media 750,to be indented.

In the process of FIG. 31, midweb darting was involved. For a midwebdarting process, generally the indentation could be caused by anarrangement analogous to the wheel 650, FIG. 32. That is, with outsidesupport and an underneath support roller that does not includecorrugated support structure.

In some systems, it may be desirable to cause indentations at an edge ofa web. In FIG. 47, an extension of web 760 is depicted. Web 760 has acenter 801 and opposite edges 802, 803. The web 750 generally comprisesa corrugated sheet 810 attached to a non-corrugated sheet 811. Acorrugation process along the center 801 can be conducted as shown inFIG. 36. A corrugation process along either one of edges 802, 803, canbe also conducted with a process analogous to that shown in FIG. 36,without inside support, as long as the indentation is directed against aridge of the corrugated media 810, in the direction toward thenon-corrugated media 811. Sealant could be prepositioned at along theedge, between the corrugated and non-corrugated media sheets 810, 811,to facilitate the process. Of course sonic welding could alternativelyto used, in some systems. In FIG. 47, indentation at edge 802 is shown.

In some instances, it may be desirable to cause the indentation to bedriven against a corrugation in an opposite direction from thenon-corrugated media. An approach to this is shown in FIG. 48. Inparticular, in FIG. 48, a web corrugated media 850 secured tonon-corrugated media 851 is shown. Along edge 855, the non-corrugatedmedia 856 is shown folded away from surface 860 of the corrugated media.This exposes surface 860 to potential engagement for corrugation. Anencapsulated process such as shown in FIG. 46, except with theindentation and outside support roller 861 engaging surface 862, and thereceiver (or inside support) roller 865 engaging surface 866, can thenbe operated to cause indenting of each of the ridges 870 in thedirection of arrow 880. After the process of darting or indenting, thenon-corrugated media 856 can then be folded back into engagement withthe corrugated media 850 along this region. With such an approach it maybe desirable to have sealant provided on the corrugated sheet beforeindentation.

In general, as long as an appropriately flexible media is used for thenon-corrugated media 851, this approach to darting can be conducted. Itwill be important to ensure that any tacking of the corrugated media tothe non-corrugated media take place at a location sufficiently spacedfrom the edge at which indentation is to occur to allow for the folds872. Typically, a distance for spacing of such tacking of at least 12 mmfrom the edge will be sufficient.

From the above techniques, an approach to creating corrugated mediawhich has been darted at both ends can be understood. For example, theapproach of FIG. 32 can be used to create a dart fold in each of theupwardly directed ridges of the media. An approach in accord with FIG.48 can be used to create a dart or fold in each of the downwardlydirected ridges in the same media. This can be used to create a mediathen which has each of the inlet flutes each folded closed at thedownstream edge; and, each of the outlet flutes folded closed at theupstream edge.

D. Alternatives to Rollers

The particular folding arrangements shown, especially indentationarrangements, are depicted utilizing preferred roller configurations. Ofcourse, alternatives can be used. For example, continuous belts can beconfigured to provide the support, if desired; and, they can be providedwith appropriate slots therein, for indentation pin arrangements toproject therethrough. However, the roller configurations depicted, whichwould typically use rollers on the order of about 150 mm to 300 mm indiameter for the indentation roller (FIG. 32) and about 150 mm to 300 mmin diameter for the receiver roller (FIG. 41), are convenient tomanufacture and use.

E. Folding

For any of the processes of FIGS. 32, 46, 47 and 48, a follow-up step offolding media points 900, 901, FIG. 36 a over, typically toward oneanother, to create the fold of FIG. 15 would be required. This can beconducted with roller 572, FIG. 31. The roller 572 would preferably beas described above.

IV. Some General Observations and Principles

In general, the techniques previously described can be used to providefor preferred fluted filter media constructions. In this context, theterm “fluted filter media construction” is meant to refer to a filterconstruction which includes the media, whether the construction is themedia itself or the media provided in the form of an overall serviceablefilter element or cartridge, for example cartridges as shown in FIGS. 26and 27.

The fluted filter media construction preferably comprises a corrugatedsheet of filter media having a curved wave pattern of corrugations,preferably a regular curved wave pattern of straight corrugations asdefined. The corrugations are such that a set of them define individualsflutes each having an end closure defined by regular fold arrangement incorresponding ones of the set of corrugations. The regular foldarrangement of each corrugation includes at least two folds. Typicallyfor the preferred arrangements described, such as shown in FIG. 15, fourfolds are provided at each corrugation which is folded closed. Forthese, two of the folds are generally upper, inwardly directed folds andtwo of the folds are generally lower, outwardly directed folds.

The typical fluted filter media construction will comprise a sheet ofcorrugated media having individual flutes each closed by a regular foldarrangement, secured to a non-corrugated sheet of filter media.Typically the filter media construction will include such a combinationof a corrugated sheet and a non-corrugated sheet configured to provide afilter cartridge having a set of inlet flutes and a set of outletflutes, the inlet flutes each being closed to passage of unfilteredfluid therethrough, adjacent the outlet face and each outlet flute beingclosed, to passage of unfiltered fluid therein, adjacent the inlet face.The term “adjacent” in this context, is meant to refer to a closure thatoccurs within a distance 20% of the total length of the flute of themost adjacent face. Preferably the closure is within 10% of the lengthof the flute, of the most adjacent face. Preferably the closure of atleast one of the sets of inlet flute and outlet flutes is by the regularfold pattern. In some instances both are closed by the regular foldpattern. When a corrugation or flute end is not closed by a fold, it maybe closed by a barrier such as a sealant barrier, or in some othermanner. Thus, in some instances a filter cartridge will contain a set offlutes folded closed at one face, and another set of flutes closed by asealant barrier at another face.

In various filter media constructions, the corrugated sheet and thenon-corrugated sheet can be jointly coiled to form a coiled mediaconstruction. The coiled media construction may be circular, or may beobround, for example race track shape. In other arrangements, the mediawould be used in the form of a stack of strips.

In a typical arrangement, the regular fold arrangement would includesome sealant herein, to facilitate and maintain closure.

Also according to the present disclosure a process for manufacturing afilter media construction including a sheet of fluted (typicallycorrugated) filter media having curved wave pattern of corrugations isprovided. The process generally includes steps of: (1) deforming aportion of a flute or corrugation to define at least one foldable tip;and (2) folding the at least one foldable tip over, to fold the flute orcorrugation closed. Typically, two foldable tips in each corrugation aregenerated, and are folded over, preferably toward one another.

Preferably the process is conducted on a sheet of corrugated mediahaving a curved wave pattern of corrugations. In many preferredapplications, the sheet of corrugated filter media is secured to a sheetof non-corrugated media, to form a continuous web, prior to the step ofindenting and folding.

The process may be conducted as a mid-web deformation and foldingprocess, with follow-up slitting. It also may be conducted along a webedge. When conducted along an edge, it can be conducted in a directiontoward the uncorrugated media, or, by folding the non-corrugated mediaout of the way, it can be conducted in a direction away from thenon-corrugated media. Of course the process can be conducted oncorrugated media that is not secured to non-corrugated media.

The deformation process can be conducted without support, or withoutside support or inside support (or both) provided to a corrugation ata location longitudinally adjacent the location or deformation. By theterm “longitudinally adjacent” in this context, it is meant that thesupport occurs in the same location as the deformation, except moved outof the way of the deformation pin arrangement which causes thedeformation.

The deformation (typically a step of indenting) can be conducted with anindenting wheel, with a step of folding comprising pressing with afolding wheel. The indenting wheel may comprise a wheel having an outercorrugated surface, to provide for outside corrugation support, with atleast one, and typically a plurality, of spaced indentation pins. Theindentation pins may be mounted with a projection/retraction arrangementthat allows the pins to be projected outwardly from the indenting wheelwhen indentation is to be conducted, and to be retracted out of the way,when desired.

In a typical process, the corrugated sheet or web would be formed bypassing a non-corrugated sheet into the bite between corrugationrollers. In some processes sealant may be provided on the corrugatedsheet prior to deformation, by providing the sealant on the web when itis passed into the corrugating rollers, to form the corrugated sheet.This can be advantageous for reasons previously discussed.

It will be understood that the techniques or principles and examplesprovided, can be provided and used in a variety of specific manners, toaccomplish the desired results. The drawings and descriptions areintended to be exemplary only.

1-18. (canceled)
 19. A fluted filter media construction comprising: (a)a corrugated sheet of filter media comprising a curved wave pattern ofcorrugations; (i) a set of the corrugations defining individual fluteseach having an end closure defined by a regular fold arrangement in acorresponding corrugation; the regular fold arrangement of eachcorrugation including at least four folds; (A) the end closure beingsealed closed to fluid flow therethrough.
 20. A fluted filter mediaconstruction according to claim 19 wherein: (a) the corrugated sheet offilter media comprises a regular, curved, wave pattern of straightcorrugations.
 21. A fluted filter media construction according to claim19 including: (a) a non-corrugated sheet of filter media secured to thecorrugated sheet of filter media.
 22. A fluted filter media constructionaccording to claim 21 wherein: (a) the corrugations have a flute/flatratio within the range of 1.2-2.0, inclusive.
 23. A fluted mediaconstruction according to claim 21 wherein: (a) the corrugated sheet andnon-corrugated sheet are positioned in a filter to define a set of inletflutes and a set of outlet flutes extending between an inlet face and anoutlet face; (i) each inlet flute being closed to passage of unfilteredfluid therethrough, adjacent said outlet face; and (ii) each outletflute being closed, to passage of unfiltered fluid therein, adjacentsaid inlet face.
 24. A fluted media construction according to claim 23wherein: (a) each inlet flute is closed, by the regular foldarrangement, adjacent the outlet face.
 25. A fluted media constructionaccording to claim 23 wherein: (a) each outlet flute is closed, by theregular fold arrangement, adjacent the inlet face.
 26. A fluted mediaconstruction according to claim 23 wherein: (a) each regular foldarrangement includes a sealant material therein.
 27. A fluted mediaconstruction according to claim 21 wherein: (a) the corrugated sheet andthe non-corrugated sheet are jointly coiled into a coiled mediastructure.
 28. A process of manufacturing a filter media constructionincluding a sheet of corrugated filter media having a curved wavepattern of corrugations; said process including steps of: (a) deforminga portion of a corrugation to define at least one foldable tip; and, (b)folding the at least one foldable tip over, to fold the corrugationclosed; (i) the closed corrugation being defined by a regular foldarrangement including at least four folds and being sealed closed tofluid flow therethrough.
 29. A process according to claim 28 wherein:(a) the corrugation which is deformed by the deforming step is a memberof a regular curved wave pattern of corrugations.
 30. A processaccording to claim 28 wherein: (a) prior to the step of deforming, thesheet of corrugated filter media is secured to a sheet of non-corrugatedfilter media to form a web of media.
 31. A process according to claim 28wherein: (a) said step of deforming is a mid-web indenting processconducted on corrugation ridges projecting away from the sheet ofnon-corrugated filter media; (b) said step of folding comprises amid-web folding process of folding the at least one foldable tip towardthe sheet of non-corrugated filter media to form a mid-web fold line;and, (c) the process includes a step of splitting the web of media alongthe mid-web fold line.
 32. A process according to claim 28 wherein: (a)the step of deforming comprises center indenting to form two foldabletips; and, (b) the step of folding comprises a step of folding the twofoldable tips toward one another.
 33. A process according to claim 28wherein: (a) the step of deforming comprises indenting with an indentingwheel; and, (b) the step of folding comprises pressing with a foldingwheel.
 34. A process according to claim 28 wherein: (a) said step ofdeforming includes indenting a selected corrugation that is supported,at a region longitudinally adjacent where deformation will occur, by asupport arrangement including at least one of: (i) an outsidecorrugation support; and (ii) an inside corrugation support.
 35. Aprocess according to claim 28 wherein: (a) the step of deforming isconducted with an indenting roller having: (i) an outer corrugatedsurface configured to provide outside support to a corrugation, duringindenting; and, (ii) a projectable/retractable indentation pinarrangement.
 36. A process according to claim 28 including steps of: (a)forming the corrugated media by passing a web of non-corrugated mediainto a bite between a pair of corrugating rollers; and, (b) applyingsealant to the corrugated media by applying the sealant before the mediais corrugated.